• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0

OpenGL Procedural Planet Generation - Quadtrees and Geomipmapping

29 posts in this topic

The tesselator as far as i can tell is not good for LoD like this. I would still need to split it into patches for the tesselator to act on. I believe the tesselation acts on the full model and not just the area near you. Not to mention the fact that not many people have access to OpenGL 4.0


Share this post

Link to post
Share on other sites
Actually I think the opposite might be true. The tessellator is very good for terrain rendering and LoD, however the shader is difficult to implement.

I started to write a spherical patch renderer based on a cubemap projection (similar to yours) several years ago (probably 2008).

I would probably get rid of the patched sphere terrain idea and use a spherical coordinate grid ( with north and south pole ) . I think its perfectly easy to divide the spherical coordinate sphere into patches based on latitude and longitude, and if you think about it, the patches will be very close to square at high resolution - the downside to this is the fact for bigger planets you have more terrain visible at each height before the horizon. However for larger worlds, you don't need to tessellate until you are quite near the surface, and then you just need fine detail on surfaces like mountains and bumpy areas. I know this might sound obvious. So you would want a method for determining the curvature variation for distant mountains, and of course they could often be rendered into a cube map and morphed. And what about the errors on the north and south pole ? Well you don't want your players to go there, they wouldn't want to go there because the poles suck, obviously. On a cubemap patch grid there are 8 problem regions with a lot of warping. So perhaps you could render a mesh over the top of the spheres - if you really wanted your players to go hunting Arctic hares for example - you could drape a patch over the top and morph the two models / artistically merge them.

edit: in fact if you remove the point at the top of a spherical coordinate grid and a couple of rings you have a circle of vertices at the top, if you think of these as like the hour marks on a clock, you can join 1 O'clock to 5 O'clock, and 2 to 4, 12 to 6 etc, and the same for the horizontal direction, so then you have an easy way to patch over the top.

Anyway the google link I posted has a terrain renderer at the top of the search. It is based in Python ... my only criticism of the source is that to run the program on my desktop PC I had various issues - first I downloaded Python 3.3 (I don't have python on my desktop computer) and nothing worked, so I downloaded Python 2.7 and found out that the library required Python 2.5, so I downloaded this, and found out that another library needed Python 2.6, so eventually when I tried to run the code - it didn't even build.

I think if you really want to use a patch system based on a cube, then I think chunked lod is the best scheme for rendering the surface - see Thatcher Ulrich's code

However I really think CPU based patches are a Kludge compared to GPU methods.

Also you might need to look into efficient mega texturing. Edited by ray_intellect

Share this post

Link to post
Share on other sites

Vangoule, on 05 Feb 2013 - 06:54, said:
The tesselator as far as i can tell is not good for LoD like this. I would still need to split it into patches for the tesselator to act on.

If you really want to go the all GPU route, you can stick your quad-tree in a vertex buffer, use a geometry shader to perform the LoD split/combine operations on the quad-tree, use transform feedback to store the result back in a vertex buffer, and use the tesselator to actually tesselate and render the various patches in the quad-tree.

I had a quick prototype of this up and running last year, and it worked pretty well, though I never got around to polishing it up for release.

Share this post

Link to post
Share on other sites

Using an actual sphere rather than using a cube seems a much harder way to actually accomplish what i'm doing. The cube system i'm using now shows no seams and the heights carry on perfectly due to the noise being 3D using the position of the vertex. The only thing i need to worry about at the moment is splitting it into patches which is the thing that's not working. GPU Tessellation would be nice but that doesn't change the fact i still need patches for it to work on. I'm at the point of ripping my hair out with this Quad Tree. The positioning just won't happen...


Share this post

Link to post
Share on other sites

Well, actually the spherical coordinate system wouldn't be as easy to map to a quad tree. Instead you could try creating large tiles in the latitude and longitude grid, these tiles could be numbered, then you could have a function that takes the visible section of the sphere and returns the tiles you need to display, Then you could select a tessellation level based on the distance between the viewer and a patch, and of course, the patches would probably subdivide, so perhaps a transform feedback approach would work.


And for your current problem of splitting into patches, perhaps have a single patch for each grid level, and use instancing to render these where they are required, so instead of splitting them into patches, perhaps you could start with a fine grid of tiles, and each tile represents a patch instance.


Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  
Followers 0

  • Similar Content

    • By Toastmastern
      So it's been a while since I took a break from my whole creating a planet in DX11. Last time around I got stuck on fixing a nice LOD.
      A week back or so I got help to find this:
      In general this is what I'm trying to recreate in DX11, he that made that planet LOD uses OpenGL but that is a minor issue and something I can solve. But I have a question regarding the code
      He gets the position using this row
      vec4d pos = b.var.vec4d["position"]; Which is then used further down when he sends the variable "center" into the drawing function:
      if (pos.len() < 1) pos.norm(); world::draw(vec3d(pos.x, pos.y, pos.z));  
      Inside the draw function this happens:
      draw_recursive(p3[0], p3[1], p3[2], center); Basically the 3 vertices of the triangle and the center of details that he sent as a parameter earlier: vec3d(pos.x, pos.y, pos.z)
      Now onto my real question, he does vec3d edge_center[3] = { (p1 + p2) / 2, (p2 + p3) / 2, (p3 + p1) / 2 }; to get the edge center of each edge, nothing weird there.
      But this is used later on with:
      vec3d d = center + edge_center[i]; edge_test[i] = d.len() > ratio_size; edge_test is then used to evaluate if there should be a triangle drawn or if it should be split up into 3 new triangles instead. Why is it working for him? shouldn't it be like center - edge_center or something like that? Why adding them togheter? I asume here that the center is the center of details for the LOD. the position of the camera if stood on the ground of the planet and not up int he air like it is now.

      Full code can be seen here:
      If anyone would like to take a look and try to help me understand this code I would love this person. I'm running out of ideas on how to solve this in my own head, most likely twisted it one time to many up in my head
      Thanks in advance
    • By fllwr0491
      I googled around but are unable to find source code or details of implementation.
      What keywords should I search for this topic?
      Things I would like to know:
      A. How to ensure that partially covered pixels are rasterized?
         Apparently by expanding each triangle by 1 pixel or so, rasterization problem is almost solved.
         But it will result in an unindexable triangle list without tons of overlaps. Will it incur a large performance penalty?
      B. A-buffer like bitmask needs a read-modiry-write operation.
         How to ensure proper synchronizations in GLSL?
         GLSL seems to only allow int32 atomics on image.
      C. Is there some simple ways to estimate coverage on-the-fly?
         In case I am to draw 2D shapes onto an exisitng target:
         1. A multi-pass whatever-buffer seems overkill.
         2. Multisampling could cost a lot memory though all I need is better coverage.
            Besides, I have to blit twice, if draw target is not multisampled.
    • By mapra99

      I am working on a recent project and I have been learning how to code in C# using OpenGL libraries for some graphics. I have achieved some quite interesting things using TAO Framework writing in Console Applications, creating a GLUT Window. But my problem now is that I need to incorporate the Graphics in a Windows Form so I can relate the objects that I render with some .NET Controls.

      To deal with this problem, I have seen in some forums that it's better to use OpenTK instead of TAO Framework, so I can use the glControl that OpenTK libraries offer. However, I haven't found complete articles, tutorials or source codes that help using the glControl or that may insert me into de OpenTK functions. Would somebody please share in this forum some links or files where I can find good documentation about this topic? Or may I use another library different of OpenTK?

    • By Solid_Spy
      Hello, I have been working on SH Irradiance map rendering, and I have been using a GLSL pixel shader to render SH irradiance to 2D irradiance maps for my static objects. I already have it working with 9 3D textures so far for the first 9 SH functions.
      In my GLSL shader, I have to send in 9 SH Coefficient 3D Texures that use RGBA8 as a pixel format. RGB being used for the coefficients for red, green, and blue, and the A for checking if the voxel is in use (for the 3D texture solidification shader to prevent bleeding).
      My problem is, I want to knock this number of textures down to something like 4 or 5. Getting even lower would be a godsend. This is because I eventually plan on adding more SH Coefficient 3D Textures for other parts of the game map (such as inside rooms, as opposed to the outside), to circumvent irradiance probe bleeding between rooms separated by walls. I don't want to reach the 32 texture limit too soon. Also, I figure that it would be a LOT faster.
      Is there a way I could, say, store 2 sets of SH Coefficients for 2 SH functions inside a texture with RGBA16 pixels? If so, how would I extract them from inside GLSL? Let me know if you have any suggestions ^^.
    • By KarimIO
      EDIT: I thought this was restricted to Attribute-Created GL contexts, but it isn't, so I rewrote the post.
      Hey guys, whenever I call SwapBuffers(hDC), I get a crash, and I get a "Too many posts were made to a semaphore." from Windows as I call SwapBuffers. What could be the cause of this?
      Update: No crash occurs if I don't draw, just clear and swap.
      static PIXELFORMATDESCRIPTOR pfd = // pfd Tells Windows How We Want Things To Be { sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor 1, // Version Number PFD_DRAW_TO_WINDOW | // Format Must Support Window PFD_SUPPORT_OPENGL | // Format Must Support OpenGL PFD_DOUBLEBUFFER, // Must Support Double Buffering PFD_TYPE_RGBA, // Request An RGBA Format 32, // Select Our Color Depth 0, 0, 0, 0, 0, 0, // Color Bits Ignored 0, // No Alpha Buffer 0, // Shift Bit Ignored 0, // No Accumulation Buffer 0, 0, 0, 0, // Accumulation Bits Ignored 24, // 24Bit Z-Buffer (Depth Buffer) 0, // No Stencil Buffer 0, // No Auxiliary Buffer PFD_MAIN_PLANE, // Main Drawing Layer 0, // Reserved 0, 0, 0 // Layer Masks Ignored }; if (!(hDC = GetDC(windowHandle))) return false; unsigned int PixelFormat; if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd))) return false; if (!SetPixelFormat(hDC, PixelFormat, &pfd)) return false; hRC = wglCreateContext(hDC); if (!hRC) { std::cout << "wglCreateContext Failed!\n"; return false; } if (wglMakeCurrent(hDC, hRC) == NULL) { std::cout << "Make Context Current Second Failed!\n"; return false; } ... // OGL Buffer Initialization glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT); glBindVertexArray(vao); glUseProgram(myprogram); glDrawElements(GL_TRIANGLES, indexCount, GL_UNSIGNED_SHORT, (void *)indexStart); SwapBuffers(GetDC(window_handle));  
  • Popular Now